(NaturalNews) For more than 60 years now, many conventional bee farmers have been dousing their hives with antibiotic drugs to prevent their bees from dying of foulbrood, a bacterial disease that has the potential to wipe out entire bee colonies if left unaddressed. But the unabated use of these drugs has had the unintended, long-term consequence of generating antibiotic-resistant genes within entire species of bees, and particularly among bees in the U.S. that have endured the longest and most substantial chemical exposures.

Similar to the type of antibiotic resistance emerging as a result of conventional rearing methods for livestock, antibiotic resistance among bees is a relatively new phenomenon, at least as far as scientific observation is concerned. A recent study published in the online, open-access journal of the American Society for Microbiology, widespread use of oxytetracycline, an antibiotic drug that disrupts the bacterial balance of bees' guts, has resulted in gradual genetic changes taking place throughout the generational cycles of bees' lives.

"[Resistance] seems to be everywhere in the U.S. There's a pattern here, where the U.S. has these genes and the others don't," said Nancy Moran, senior author of the study from Yale University. "It seems likely this reflects a history of using oxytetracycline since the 1950s. It's not terribly surprising. It parallels findings in other domestic animals, like chickens and pigs."

Utilizing sensitive molecular techniques, Moran and her colleagues conducted a comparative analysis of U.S. bees, as well as bees obtained from Switzerland, the Czech Republic, New Zealand, and elsewhere. Based on the results of a comprehensive gene analysis, the team determined that U.S. bees had the highest number, and most diverse set, of genes with resistance to tetracycline, which is similar in structure to oxytetracycline.

In Switzerland, the Czech Republic, and New Zealand, where the use of oxytetracycline is banned, bees were generally observed to have only two or three resistance genes on average. But in the U.S., where oxytetracycline continues to be permitted for use in hives, bees were found to have as many as eight antibiotic-resistance genes, which has made them more prone than ever to foulbrood and other deadly pathogens.

"Studies have suggested that the bacterial residents of the honeybee gut play beneficial roles in neutralizing toxins in the bees' diet, nutrition, and in defending the bee against pathogens," states a press release about the study. "By disrupting the honeybee microbiota and reducing its diversity, long-term antibiotic use could weaken honeybee resistance to other diseases."